Emergency lighting systems are usually installed in public buildings such as, for example, theaters, hospitals, schools and public shelters, in industrial buildings such as, for example, plants and warehouses and residence buildings, apartments and basements. Most of the known emergency lighting systems may activate the lighting whenever a power failure or interruption occurs.
A block diagram of a currently available emergency lighting system 100 is illustrated in FIG. 1. System 100 is powered by power source 112 and may include a light source 110, a, charger 116, battery 118, an electronic switching mechanism for example, SPDT relay 114, and relay switch 115. It is noted that the relay configuration is one of many options known in the art, and other or additional known electronic components may be used such as transistors, thyristors, silicon controlled resistors (SCR), triacs, and others. Under normal operation, charger 116 may charge battery 118 and the light may turn off. When a power failure occurs, relay coil 114 may be deactivated, relay switch 115 may connect light source 110 to battery 118 and the light may turn on. It will be noted that in the event that the battery voltage is not compatible with the lamp voltage, a voltage conversion may be is needed between battery 118 and lamp 110.
When the power failure ends, relay coil 114 may be activated, thus turning the light off and charger 116 may draw power from power source 112 to charge battery 118 back to fully charged state. Typically, the amount of power may be up to twice the power delivered to light source 110 due to the efficiency of charger 116 and the requirements of battery 118. This emergency lighting system may require two wires from the continuous power source to operate and may be mounted in addition to the light source (power operated bulb) controlled by the on/off switch mounted inside the room.
Some dual purpose emergency lighting systems may enable combining the regular room light source with the emergency light, in such way that they enable the light source to turn on according to the light switch, but activate the light source to work on batteries when there is a power failure. FIG. 2 illustrates a currently available dual purpose emergency lighting system 200. System 200 may include a power source 222, a light switch 220, a charger 224, a battery 226, a voltage converter 227, an electronic switch control mechanism 228, for example, a DPDT relay, a relay switch 225 and a light source 229. System 200 arrangement may require three wires connection and may need special installation preparation, and thus it cannot be simply connected to an existing bulb installation. When power source 222 is active, relay coil 228 may operate switch 225 to connect light source 229, for example, in series, to light switch 220, thus enabling light source 229 to work according to the position of switch 220. When power source 222 is not active, the relay coil 228 may be deactivated, thus connecting light source 229 to the output of voltage converter 227. Voltage converter 227 may be used to boost up the low voltage of battery 226, to match the type and specifications of light source 229. During a power failure battery 226 may be discharged by voltage converter 227 in order to power the light source 229. When the power failure ends, relay coil 228 may reconnect light source 229 to light switch 220 and charger 224 may start charging battery 226 to full capacity.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.